The subject invention concerns a device for regulation of the transfer of heat in a heat pipe by means of an operative medium contained in the pipe. The heat pipe is of the kind comprising a heat-emitting condenser element, a heat-absorbing evaporator element and an interconnecting conduit joining said two elements together. The regulator means comprises a valve seat which is formed on the interior face of the heat pipe, and a valve body which cooperates with said valve seat to open and close the valve opening formed between said valve body and said valve seat. A member consisting of a configuration memory alloy is connected to the valve body and is arranged to alter its configuration upon the attainment of a predetermined temperature and in doing so, cause the valve body to open or close the valve opening.
Prior-art heat pipes of this kind suffer from the disadvantage of not being able to provide distinct valve closing and opening positions. One example of a prior-art structure is the device disclosed in U.S. Pat. No. 4,693,306. The device shown therein consists of a pipe which is formed with a valve flange and which is arranged to sealingly seat against an interior annular portion of the condenser element. The valve opening and closing movements are controlled by the expansions and contractions of the pipe forming the valve and by those of the condenser element body, which components are made from materials having different coefficients of thermal expansion. Because of this arrangement, the valve will open and close as the result of thermal variations when one part, the condenser element, expands to a larger extent than the other part, the pipe. However, this arrangement does not provide distinct opening or closing movements and therefore sufficiently accurate control of the thermal flow inside the heat pipe is not possible with this prior-art structure.
Another problem encountered in the structure disclosed in U.S. Pat. No. 4,693,306 is that it calls for very careful and complex manufacturing and assembly procedures if the desired sealing effect is to be obtained between the valve and its associated seat. Since both the valve and the seat are fixedly secured to the condenser element the spatial interrelationship of these components must be absolutely accurate to ensure that the closure of the valve opening occurs at the desired temperature. In this structure, the closing temperature depends entirely on the spacing of the valve from its associate seat under cold conditions. Since comparatively small movements are involved in the process extremely high-precision assembly is required as regards heat pipes of this construction.